US9702891B2 - Analogue amplification device intended in particular for a laser anemometer - Google Patents

Analogue amplification device intended in particular for a laser anemometer Download PDF

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US9702891B2
US9702891B2 US14/423,402 US201314423402A US9702891B2 US 9702891 B2 US9702891 B2 US 9702891B2 US 201314423402 A US201314423402 A US 201314423402A US 9702891 B2 US9702891 B2 US 9702891B2
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transistor
amplification device
supply
analogue
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US20150233961A1 (en
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Francis Bony
Raphael Teysseyre
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Institut National Polytechnique de Toulouse INPT
EPSILINE
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/04—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements with semiconductor devices only
    • H03F3/08—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements with semiconductor devices only controlled by light
    • H03F3/087—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements with semiconductor devices only controlled by light with IC amplifier blocks
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P5/00—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft
    • G01P5/26—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft by measuring the direct influence of the streaming fluid on the properties of a detecting optical wave
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/56—Modifications of input or output impedances, not otherwise provided for
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/45—Differential amplifiers
    • H03F3/45071—Differential amplifiers with semiconductor devices only
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/45—Differential amplifiers
    • H03F3/45071—Differential amplifiers with semiconductor devices only
    • H03F3/45076—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier
    • H03F3/45475—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier using IC blocks as the active amplifying circuit
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/50—Amplifiers in which input is applied to, or output is derived from, an impedance common to input and output circuits of the amplifying element, e.g. cathode follower
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2200/00—Indexing scheme relating to amplifiers
    • H03F2200/285—Indexing scheme relating to amplifiers the level shifting stage between two amplifying stages being realised by an emitter follower
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2200/00—Indexing scheme relating to amplifiers
    • H03F2200/405—Indexing scheme relating to amplifiers the output amplifying stage of an amplifier comprising more than three power stages
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2200/00—Indexing scheme relating to amplifiers
    • H03F2200/42—Indexing scheme relating to amplifiers the input to the amplifier being made by capacitive coupling means
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2200/00—Indexing scheme relating to amplifiers
    • H03F2200/54—Two or more capacitor coupled amplifier stages in cascade
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2200/00—Indexing scheme relating to amplifiers
    • H03F2200/555—A voltage generating circuit being realised for biasing different circuit elements
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2200/00—Indexing scheme relating to amplifiers
    • H03F2200/69—Indexing scheme relating to amplifiers the amplifier stage being a common drain coupled MOSFET, i.e. source follower
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2200/00—Indexing scheme relating to amplifiers
    • H03F2200/72—Indexing scheme relating to amplifiers the amplifier stage being a common gate configuration MOSFET
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
    • H03F2203/45—Indexing scheme relating to differential amplifiers
    • H03F2203/45051—Two or more differential amplifiers cascade coupled
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
    • H03F2203/45—Indexing scheme relating to differential amplifiers
    • H03F2203/45112—Indexing scheme relating to differential amplifiers the biasing of the differential amplifier being controlled from the input or the output signal
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
    • H03F2203/45—Indexing scheme relating to differential amplifiers
    • H03F2203/45528—Indexing scheme relating to differential amplifiers the FBC comprising one or more passive resistors and being coupled between the LC and the IC
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
    • H03F2203/45—Indexing scheme relating to differential amplifiers
    • H03F2203/45544—Indexing scheme relating to differential amplifiers the IC comprising one or more capacitors, e.g. coupling capacitors
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
    • H03F2203/45—Indexing scheme relating to differential amplifiers
    • H03F2203/45594—Indexing scheme relating to differential amplifiers the IC comprising one or more resistors, which are not biasing resistor
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
    • H03F2203/50—Indexing scheme relating to amplifiers in which input being applied to, or output being derived from, an impedance common to input and output circuits of the amplifying element, e.g. cathode follower
    • H03F2203/5036—Indexing scheme relating to amplifiers in which input being applied to, or output being derived from, an impedance common to input and output circuits of the amplifying element, e.g. cathode follower the source follower has a resistor in its source circuit

Definitions

  • the present invention relates to an analogue amplification device intended in particular for a laser anemometer such as, for example, a laser anemometer with optical retro-injection.
  • the present invention is therefore in the field of electronic devices and more particularly of amplification devices. It is conventional to have a sensor for measuring a physical magnitude. This sensor thus supplies an electrical signal that represents the physical magnitude measured. Some sensors supply electrical signals that can be directly used. For other sensors, the supplied signal must be amplified before it can be used.
  • amplification devices that present at the same time an elevated gain, a wide bandwidth and low noise.
  • These amplification devices are intended for treating signals presenting a very weak modulation index. This means that the variations of the signal are very weak relative to the average value of the signal. Therefore, the signal is buried in the inherent noise in any case.
  • a photodiode In a laser anemometer, a photodiode is used as measuring sensor. It receives the incident beam and the reflected beam and emits a corresponding signal. The signal corresponding to the reflected beam is very weak in comparison to the signal corresponding to the incident beam. In such an anemometer, the part corresponding to the reflected beam in the supplied signal should be detected.
  • a laser anemometer is disclosed, for example, in the document WO-2011/042678.
  • the device described in this document comprises means for transmitting a laser beam, called the transmitted beam, means for focusing the transmitted beam at a predetermined focusing distance, means for receiving the transmitted beam after being reflected by a particle present in the air, called the reflected beam, and means for the transmission of the signal of interferences intervening between the transmitted beam and the reflected beam by means of processing the signal in order to deduce the speed of the particle.
  • the transmission means comprise a laser diode and the receiving means is associated with the laser diode by self-mixing.
  • Such an anemometer is also called a laser anemometer with optical retro-injection.
  • Document DE-26 43 892 discloses an amplifying circuit presenting, on the one hand, a transistorized stage with a common base setup as output stage and, on the other hand, a transistorized attack stage with a common collector setup, wherein the attack stage and the output stage are connected by a matching circuit comprising an input impedance greater than its output impedance.
  • the circuits proposed in this document have a significant input impedance. If such an impedance is coupled to a junction capacitance of a photodiode, the bandwidth of the system will be greatly limited.
  • One goal of the present invention is therefore to obtain a lower noise level (for example, lower than with a transimpedance amplifier comprising an operational amplifier) while retaining satisfactory gain, bandwidth, and impedances of input/output, and advantageously a stable behavior without the risk of oscillations.
  • the invention has the goal of supplying an amplification device having excellent performance and that can be used in particular for an optoelectronic detection module of a laser anemometer with optical retro-injection.
  • an amplification device in accordance with the present invention can also be used in other applications in which a weak signal is superposed on a larger signal.
  • the device in accordance with the present invention preferably has a large bandwidth.
  • the noise of the amplification device defined by its spectral density of noise power, should be limited.
  • the gain supplied by the amplification device it should be significant.
  • the amplification device is preferably provided with a supply that does not disturb the good performance of the amplification device with which it is associated.
  • the amplification device receives a modulated current stemming from a photodiode constituting the sensor of the laser anemometer.
  • the noise of the amplification device returned to the input should then be greater than the noise of the photodiode.
  • the gain of the amplification device should be such that the output noise of the latter is significantly greater than the noise of the analogue/digital converter used in the detection module associated with the anemometer.
  • an analogue amplification device comprising four stages in a cascade, an input for receiving a modulated current, and an output under voltage, which device comprises a ground and a supply voltage.
  • This structure with several stages allows a significant gain and the use of transmitters such as mentioned permits the obtention of performances that cannot be obtained by using amplification devices with an operational amplifier.
  • the novel structure proposed here allows a noticeable increase of the performances for the measurements of wind speeds that are carried out.
  • the present invention can be carried out with “conventional” transistors that can comprise a base, an emitter and a collector or also with field effect transistors comprising for their part a gate, a source and a drain.
  • the emitter in the first stage, is also connected to the ground by a resistor in that the base is connected to the ground by a capacitor and in that the potential of the base is maintained at a potential close to the ground, and that the collector is connected by a resistor to the supply voltage.
  • An advantageous form of the invention provides that in the third stage, the base or the gate is biased at a voltage close to the voltage of the ground in that the emitter or the source is connected by an RC circuit to the ground and that the collector or the drain is connected to the supply voltage by a resistor.
  • the fourth stage can comprise an operational amplifier that receives the output signal of the third stage on its non-inverted input via a capacitor, wherein the output of the amplifier corresponds to the output of the amplification device.
  • the inverted input of the operational amplifier is connected to the ground by a resistor and by a capacitor in series, that the output is connected to the inverted input by a resistor, and that the non-inverted input of the operational amplifier is biased at a voltage corresponding approximately to one half of the supply voltage.
  • a variant can provide that the fourth stage comprises, on the one hand, an amplification circuit with a transistor, and on the other hand, a follower circuit, possibly also with a transistor.
  • the amplification circuit can comprise, for example, a common emitter (or source) setup and the follower setup can be the type of setup proposed for the second stage.
  • the operational amplifier used here is preferably an amplifier with counter-reaction current that has better dynamic performances than an operational amplifier with counter-reaction voltage.
  • the different architectures proposed here for the fourth stage permit the simultaneous realization of an amplification and a matching of impedance.
  • the transistor used in the first stage is advantageously a transistor of the NPN type because such a transistor has a transition frequency greater than that of a PNP transistor.
  • the transistor of the second stage preferably has the same characteristics as the transistor of the first stage. Therefore, its added charge capacity is close to its base collector capacity, which causes a drop of the cutoff frequency by a factor of 2.
  • the transistor of the third stage has the same characteristics as the transistor of the first stage.
  • the present invention also relates to a unit formed by an analogue amplification device and to a supply system of this analogue amplification device, characterized in that the analogue amplification device is a device such as that described above, and in that the supply system comprises, on the one hand, an input filter and, on the other hand, a filtering module that simultaneously allows an insulation and a low frequency decoupling and an insulation and a high frequency decoupling between the input filter and each stage of the amplification device.
  • the supply system comprises, on the one hand, an input filter and, on the other hand, a filtering module that simultaneously allows an insulation and a low frequency decoupling and an insulation and a high frequency decoupling between the input filter and each stage of the amplification device.
  • Each filtering module comprises, for example, a supply track on which are advantageously located, on the one hand, a linear regulator and, on the other hand, a ferrite. This structure allows a good insulation and a good decoupling to be ensured.
  • the present invention also relates to a Doppler-effect laser anemometer with optical retro-injection comprising a laser diode for transmitting a laser beam, a lens for focusing, on the one hand, a beam transmitted by the laser diode and, on the other hand, a beam reflected by a particle located in a volume called the measuring volume, which reflected beam corresponds to a beam transmitted by the laser diode, a photodiode for receiving this reflected beam after it has traversed the laser diode, means for the amplification of a signal supplied by the photodiode as well as means for processing the amplified signal.
  • Such an anemometer according to the invention is characterized in that the amplification means comprises an analogue amplification device such as that described above.
  • FIG. 1 schematically illustrates the principle of a laser anemometer with optical retro-injection
  • FIG. 2 schematically shows a string for the acquisition of such a laser anemometer
  • FIG. 3 is a diagram schematically illustrating an amplification device according to the present invention.
  • FIG. 4 is an example of an embodiment of a first stage of an amplification device according to the present invention.
  • FIG. 5 is a schematic drawing of an example of a second stage of an amplification device according to the present invention.
  • FIG. 6 is a schematic drawing of an example of a third stage of an amplification device according to the present invention.
  • FIG. 7 is a schematic drawing of an example of a fourth stage of an amplification device according to the present invention.
  • FIG. 8 illustrates a supply device that can be associated with an amplification device according to the present invention
  • FIG. 9 schematically shows an input filter of the supply device of FIG. 8 .
  • FIG. 10 shows a filter of the supply device of FIG. 8 for being associated with a state of the amplification device according to the present invention.
  • FIG. 1 illustrates a Doppler-effect laser anemometer with optical retro-injection.
  • Such an anemometer uses a retrodiffused signal by a particle carried by the wind for calculating the value of the wind speed.
  • a laser diode 2 for transmitting a laser beam can be recognized in FIG. 1 .
  • This laser diode 2 comprises an optical cavity in which the beam is generated.
  • the beam transmitted by the laser diode 2 is focused by an optical system 4 toward a measuring region 6 .
  • a particle located in the measuring region 6 will reflect the incident beam that will be redirected by the optical system 4 toward the laser diode 2 . Therefore, the reflected beam traverses the laser diode 2 and interacts with the laser wave inside the optical cavity of the laser diode 2 .
  • the photodiode 8 receives a laser beam corresponding to the interacting mixture of the laser wave and of the wave that is reflected or retro-diffused by a particle located in the measuring region 6 .
  • the power of the beam that is reflected or retro-diffused by a particle located in the measuring region 6 is quite less than the power of the beam transmitted by the laser diode 2 .
  • P 0 the power of a laser beam exiting directly from the laser diode 2
  • the Doppler frequency is expressed by the formula:
  • ⁇ ⁇ ⁇ f 2 ⁇ ⁇ ⁇ V ⁇ ⁇ u ⁇ ⁇
  • ⁇ right arrow over (v) ⁇ is the speed vector of the particle considered as the speed vector of the wind.
  • ⁇ right arrow over (u) ⁇ is the unit vector corresponding to the optical axis or also the propagation axis of the laser beam.
  • ⁇ right arrow over (V) ⁇ right arrow over (u) ⁇ is the scalar product giving the projection of the speed vector on the axis of the laser beam.
  • ⁇ is the wavelength of the laser.
  • n is the index of modulation and frequency created by the interaction.
  • the modulation index m of the signal is a function of parameters connected, on the one hand, to the detection configuration and, on the other hand, to the laser diode.
  • the photodiode 8 then has the function of transforming the modulated optical power (P 2 ) into a modulated current.
  • the current is then amplified in order to obtain a voltage.
  • the modulation index is weak, the signal is buried in the noise even after amplification.
  • the ratio of signal to noise can be sufficient and the signal spectrum can contain a peak above the noise level that corresponds to the Doppler frequency if the signal-to-noise ratio is sufficient. Therefore, it is possible to find the Doppler frequency corresponding to the peak by applying a Discrete Fourier transform (DFT) and therefore deduce the wind speed from it.
  • DFT Discrete Fourier transform
  • FIG. 2 illustrates an acquisition string for a laser anemometer, but similar devices are found on other electronic devices, especially measuring devices.
  • analogue card 10 on the left in FIG. 2 on which the laser diode 2 and the photodiode 8 are found.
  • This analogue card 10 also supports an amplification device called amplifier 12 in the following, which will be described in more detail below.
  • the amplifier 12 has the purpose of supplying an electrical signal that can be used by a digital card 14 for processing the amplified signal.
  • FIG. 2 shows an example of a digital card that is illustrated very schematically here.
  • a low-pass filter 16 is located, for example, at the input of this card.
  • An analogue/digital converter, also known as ADC 18 is located downstream from this filter and is followed by a programmable gate array also known by the English acronym FPGA 20 (for Field Programmable Gate Array).
  • FPGA 20 for Field Programmable Gate Array
  • Several modules are located within this FPGA 20 for carrying out various calculations such as, for example, carrying out a Fourier transformation, using the results of this transformation, etc.
  • a communication module 22 puts the results in a normalized format in such a manner that they can be used by a data recorder or a computer 24 , for example, a personal computer.
  • FIG. 3 shows a schematic illustration of the amplifier 12 .
  • This figure also shows a current generator 26 that supplies a current i(t) to the amplifier 12 .
  • the latter comprises a first stage 28 , a second stage 30 , a third stage 32 and a fourth stage 34 .
  • There is a voltage V 1 (t) at the output of the first stage 28 a voltage V 2 (t) at the output of the second stage, a voltage V 3 (t) at the output of the third stage, and a voltage Vs(t) at the output of amplifier 12 .
  • This amplifier 12 first carries out a current-voltage conversion in the first stage 28 .
  • the second stage 30 it carries out a matching of impedance that is necessary in order to prevent the gain obtained in the first stage 28 from dropping.
  • This second stage 30 serves as an interface between the first stage 28 and the third stage 32 , that is, a stage of supplementary amplification.
  • the fourth stage 34 proposed here has the purpose of again increasing the gain of the global string and allowing a matching of impedance before the sampling of the signal in the digital card 14 .
  • This first stage 28 receives the current i(t) at the input.
  • This first stage 28 is realized around a transistor 36 in a common base type setup. Such a setup supplies a good bandwidth and a significant gain at the same time. Furthermore, it supplies a significant stability compared, for example, to using an operational amplifier (used in the prior art).
  • the transistor 36 used here is a conventional transistor comprising a base, an emitter, and a collector. It could, however, also be a transistor with field effect (like the other transistors of the amplification device described here).
  • the current i(t) is sent to the emitter of the transistor 36 passing through a first capacitor C 1 .
  • the emitter of the transistor 36 is also connected to the ground by a first resistor R 1 .
  • This resistor serves to fix the current in the emitter of the transistor 36 .
  • This current is fixed, for example, at 0.25 mA, in order to limit the deterioration of the signal-to-jamming ratio for noise.
  • the collector of the transistor 36 is connected to a supply voltage Vcc via a second resistor R 2 . This resistor serves to fix the gain of the first stage 28 .
  • the base of the transistor 36 is maintained at a constant potential by resistors R 3 and R 4 .
  • the resistor R 3 is connected between the base of the transistor 36 and the ground, whereas the resistor 34 is connected between the base of the transistor 36 and the supply voltage Vcc.
  • a capacitor C 2 is also provided at the level of the base of the transistor 36 , which capacitor plays the part of a decoupling capacitor. This capacitor C 2 is connected between the base of the transistor 36 and the ground.
  • Such a setup allows the transition capacitance of the base/collector junction to be minimized. In a dynamic regime, this connection is viewed as a ground.
  • the input impedance of the setup is the dynamic resistance of the base emitter function.
  • the output impedance of this setup is R 2 .
  • the continuous current is suppressed by the decoupling capacitor C 2 . Therefore, the bias of the setup is not a function of the bias of the photodiode 8 .
  • the transistor 36 is preferably an NPN transistor because its transition frequency is greater than that of a PNP transistor.
  • FIG. 5 illustrates an embodiment of the second stage 30 .
  • the second stage carries out a matching of impedance in order to prevent the gain of the first stage 28 from falling while connection it to the third stage 32 .
  • This second stage 30 comprises a transistor 38 that is preferably identical to the transistor 36 of the first stage.
  • the setup is different since it is a common collector setup.
  • the current is fixed by the voltage of the first stage 28 and by the value of a resistor R 5 mounted between the emitter of the transistor 38 and the ground, because this stage does not have connecting capacity.
  • the follower setup represented in FIG. 5 adds a charge capacity to the first stage 28 that lowers the cut-off frequency of the first one.
  • the third stage 32 is shown in FIG. 6 .
  • This stage is a stage of supplementary amplification for augmenting the global gain of the amplifier 12 .
  • the transistor 40 itself preferably has the same dynamic characteristics as the transistor 36 of the first stage. Therefore, the transistor 40 can ensure a significant gain and a broad bandwidth by its transition frequency and its low junction capacitance.
  • a bias array with resistances R 6 and R 7 fixes a voltage of the base as close as possible to the ground in order to minimize the transition capacitance of the base collector junction.
  • the resistor R 6 is mounted between the base of the transistor 40 and the supply source Vcc, whereas the resistor R 7 is mounted between the base of the transistor 40 and the ground. In order to have a voltage close to the ground, the resistor R 7 is very weak relative to the resistor R 6 .
  • a capacitor C 3 allows the bias points of the two stages to be dissociated, and therefore to realize the controls of the parameters of the third stage 32 without taking into account the parameters of the second stage 30 .
  • a resistor R 8 mounted between the emitter and the ground allows the current to be fixed that will circulate in the transistor 40 .
  • the value of this current is fixed, for example, at 1 mA.
  • the resistor R 8 is decoupled.
  • a resistor R 9 mounted between the collector of the transistor 40 and the supply voltage Vcc allows the gain of the amplifier stage to be fixed. This resistor R 9 also supplies the output impedance of this third stage 32 .
  • FIG. 7 shows a proposed setup for realizing the fourth stage 34 .
  • This is realized around an operational amplifier 42 .
  • the signal coming from the third stage 32 arrives at the non-inverted input of the operational amplifier 42 after having passed through a capacitor C 4 for eliminating the continuous component of this signal.
  • the non-inverted input of the operational amplifier 42 can therefore be biased by an array of resistors R 10 and R 11 .
  • the resistor R 10 is mounted between the non-inverted input of the operational amplifier 42 and the supply voltage Vcc, whereas the resistor R 11 is connected between the non-inverted input of the operational amplifier 42 and the ground.
  • a bias of this non-inverted input is realized at a voltage of Vcc/2.
  • the output of the operational amplifier is connected to its inverted input by a resistor R 13 .
  • the inverted input of the operational amplifier 42 is also connected to the ground by a resistor R 12 and a capacitor C 5 .
  • the addition of this capacitor avoids the amplification of continuous voltages and therefore allows the offset voltage of the operational amplifier not to be taken into account.
  • the resistors R 12 and R 13 allow the gain of the fourth stage 34 to be fixed.
  • An operational amplifier 42 with counter-reaction current is preferably used here in order to have available better dynamic performances relative to a conventional operational amplifier with counter-reaction voltage.
  • Such an operational amplifier 42 also has the advantage of not having a high-impedance inverted input, which allows the avoidance of the couplings by electrical fields on this input.
  • the fourth stage ensures a function of amplification and a function of matching of impedance.
  • the amplifier 12 is obtained by mounting the different stages described above in cascade. For example, it is possible to obtain a gain of 53 dB at the level of the first stage 28 . As for the third stage 32 , it can have a gain of 28 dB. Finally, the fourth stage can have a gain of 23 dB. A gain of 104 dB is globally obtained for the amplifier 12 with these digital values, given purely by way of illustration and in a non-limiting manner.
  • the bandwidth of this amplifier is, for example, 125 MHz, while its spectral density of noise power is, for example, 8 ⁇ 10 ⁇ 23 A 2 /Hz.
  • the present description proposes supplying the amplifier 12 by a supplying device that supplies a constant voltage.
  • a supplying device that supplies a constant voltage.
  • the product of the gain by the bandwidth is elevated and brings about a great risk of oscillation.
  • the risk is then having a disturbance of the supply that is coupled back into the input stage.
  • this amplifier 12 if an external disturbance intervenes on the supply, this disturbance is then amplified at the output of the amplifier and would then disturb the output signal, rendering further analysis impossible.
  • the circuit supplying the amplifier should preferably be such that its impedance as seen by the active components, between a supply rail of this array and its ground, is the weakest possible.
  • the impedance of the supply rail between two active components should, for its part, be as large as possible in order to minimize the influence of one stage of the amplifier on another stage of the amplifier.
  • the circuit supplying the amplifier is preferably such that all the external disturbances are filtered at the input onto the analogue card.
  • FIG. 8 schematically illustrates an original supply circuit for the amplifier described above.
  • the selection is made here to independently supply each stage of the amplifier with the goal of maximizing the impedance between each stage that is sent fed through a dedicated regulator and a dedicated ferrite.
  • the regulator then has the goal of insulating the stages between themselves at low frequencies (for example ⁇ 1 MHz), whereas the ferrite allows the insulating of the stages between themselves at high frequencies (for example, >1 MHz).
  • the circuit shown in FIG. 8 comprises first of all a supply connector 44 that connects the supply circuit to an energy source.
  • the supply circuit comprises at the input an input filter 46 that is represented in more detail in FIG. 9 .
  • FIG. 8 shows two supply blocks of the four necessary for the amplifier 12 .
  • FIG. 10 illustrates an example of a supply block.
  • Each supply block supplying a stage of the amplifier 12 comprises a first module 48 producing a low-frequency insulation and a low-frequency decoupling, a second module 50 producing a high-frequency insulation, and a third module 52 producing a high-frequency decoupling.
  • the input filter 46 shown in FIG. 9 is dimensioned for functioning in an optimal manner in the bandwidth of the amplifier 12 . It is placed at the input of the setup in order to immunize the entire circuit against the external disturbances conducted at the card input, which disturbances can be, for example, a decoupling of the upstream supply, a coupling of the emissions conducted and radiated by the digital part of the system, a coupling of external waves (for example, radio emissions), etc.
  • This input filter 46 is therefore realized in such a manner as to maximize the losses for a parasitic signal traversing the supplies.
  • the supply connector 44 supplies potentials Vcc_d and GND_d that are then found at the input of the input filter 46 , on the left in FIG. 9 .
  • a potential 54 sometimes called SHIELD, symbolizes the mechanical ground (and the shielding) of the system.
  • Capacitors C 6 and C 7 in conjunction with a filter L 1 permit the filtering of the common mode of the supplies of the amplifier stages relative to the mechanical ground. Furthermore, capacitors C 8 and C 9 in conjunction with the filter L 1 permit, for their part, the filtering of the differential mode.
  • the input filter 46 realized in this manner should function efficiently in the bandwidth of the amplifier 12 .
  • the input filter should function efficiently over a range of frequencies from 100 kHz to at least 150 MHz.
  • the impedance of the capacitors C 6 , C 7 , C 8 and C 9 must therefore be as weak as possible on this frequency band (lower than 1 ⁇ ), and the impedance of the filter L 1 here must be as strong as possible (greater than 1 ⁇ ), which applies in the common mode as well as in the differential mode.
  • this input filter 46 then furnishes potentials Vcc and GND that are then “cleaned” of parasites potentially conducted by the supplies Vcc_d and GND_d.
  • a supply block is provided for each of the amplifier stages. Such a supply block is illustrated in FIG. 10 .
  • a linear regulator U 1 , with associated decoupling capacitors C 11 and C 12 .
  • This regulator is provided for supporting the current consumed by the corresponding stage (typically less than 50 mA).
  • a regulator known by the regulator name LDO (English acronym for Low DropOut for a low voltage drop) allows a low voltage drop to be preferred in order to lose the least power possible.
  • the regulators generally allow insulation greater than 30 dB up to frequencies on the order of a megahertz (the exact values depend on the regulators selected): the insulation between two stages is then 60 dB to frequencies on the order of a megahertz.
  • a ferrite FB 1 that has, for example, for the digital values given, an impedance greater than 100 ⁇ from several megahertz up to 150 MHz (and more if possible).
  • this ferrite FB 1 is placed in series on the supply track.
  • a capacitor C 13 is placed in parallel between the supply track and the ground.
  • This capacitor C 13 preferably has an impedance lower than 1 ⁇ from several megahertz to 150 MHz (for the digital example above).
  • the ferrite FB 1 also prevents the resonance of the capacitor C 12 with the capacitor C 13 .
  • the supply circuit presented here and illustrated by FIGS. 8-10 allows the following functions to be realized over the entire useful bandwidth of the amplifier 12 : insulation against external disturbances, insulation of the different stages among themselves, and a supply impedance viewed by the active components that is sufficiently weak to guarantee their good functioning.

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US14/423,402 2012-08-23 2013-08-14 Analogue amplification device intended in particular for a laser anemometer Active 2034-03-18 US9702891B2 (en)

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FR1257945 2012-08-23
FR1257945A FR2994776B1 (fr) 2012-08-23 2012-08-23 Dispositif d'amplification analogique destine notamment a un anemometre laser
PCT/FR2013/051944 WO2014029942A1 (fr) 2012-08-23 2013-08-14 Dispositif d'amplification analogique destine notamment a un anemometre laser

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JP6507980B2 (ja) * 2015-10-07 2019-05-08 富士通株式会社 光受信回路、光トランシーバ、および光受信回路の制御方法
US10359450B1 (en) * 2017-01-10 2019-07-23 Keysight Technologies, Inc. Current sensing probe incorporating a current-to-voltage conversion circuit
CN108802425A (zh) * 2018-07-27 2018-11-13 成都信息工程大学 一种机载风速测量激光雷达系统
CN111030699A (zh) * 2018-10-09 2020-04-17 西安智盛锐芯半导体科技有限公司 一种信号转换器
CN112946315B (zh) * 2021-02-10 2022-09-16 复旦大学 一种无电磁流量计的流速计

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WO2012070777A2 (fr) 2010-11-22 2012-05-31 서강대학교 산학협력단 Détecteur multicanal comportant un nombre réduit de canaux de sortie
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US5438305A (en) 1991-08-12 1995-08-01 Hitachi, Ltd. High frequency module including a flexible substrate
US20040263376A1 (en) * 2003-04-09 2004-12-30 Sony Corporation Comparator, sample-and-hold circuit, differential amplifier, two-stage amplifier, and analog-to-digital converter
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CA2881524C (fr) 2021-06-29
WO2014029942A1 (fr) 2014-02-27
US20150233961A1 (en) 2015-08-20
CA2881524A1 (fr) 2014-02-27
FR2994776A1 (fr) 2014-02-28
CN104937840A (zh) 2015-09-23
FR2994776B1 (fr) 2016-12-23

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